تعريف ومعنى "[let] the cat out of the bag"

What is the origin of the idiom "champagne taste on a beer budget" and when to use it?

The idiom "champagne taste on a beer budget" originated from the concept of having expensive or luxurious preferences but limited financial means. Champagne, known for its association with wealth and luxury, represents extravagant and refined tastes, while a beer budget implies having a modest or restricted amount of money to spend. The phrase highlights the contrast between one's desired lifestyle or preferences and their actual financial resources, emphasizing the need to adjust expectations or desires within the limitations of their budget.